The 20” Pentek Big Blue Housing with 1” inlet is an extra-wide housing that accommodates large 4 1/2" wide filters for increased flow. Big Blue filter housings offer the versatility to meet all of your large-capacity filtration needs, including high-flow and heavy-sediment applications. The extra large housing allows for greater cartridge capacity, reducing the number of vessels required for high-flow rate applications. Big Blue Housings are compatible with a broad range of chemicals. Reinforced polypropylene housings have excellent chemical resistance and are ideal for many residential, commercial and industrial applications.The product is tested and certified by NSF International to NSF/ANSI Standard 42 for material and structural integrity requirements.